The Collaborative International Dictionary of English v.0.48:

Infanticide \In*fan"ti*cide\, n. [L. infanticidium child murder;
   infans, -antis, child + caedere to kill: cf. F. infanticide.
   See Infant, and Homicide.]
   The murder of an infant born alive; the murder or killing of
   a newly born or young child; child murder.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Infanticide \In*fan"ti*cide\, n. [L. infanticida: cf. F.
   infanticide.]
   One who commits the crime of infanticide; one who kills an
   infant.
   [1913 Webster]

WordNet (r) 3.0 (2006):

infanticide
    n 1: a person who murders an infant
    2: murdering an infant

Bouvier's Law Dictionary, Revised 6th Ed (1856):

INFANTICIDE, med. juris. The murder of a new born infant, Dalloz, Dict.
Homicide, Sec. 4; Code Penal, 300. There is a difference between this
offence and those known by the name of prolicide, (q.v.) and foeticide.
(q.v.)
     2. To commit infanticide the child must be wholly born; it is not.
Sufficient that it was born so far as the head and breathed, if it died
before it was wholly born. 5 Carr. & Payn. 329; 24 Eng. C. L. Rep. 344; S.
C. 6 Carr: & Payn. 349; S. C. 25 Eng. C. L. Rep. 433.
     3. When this crime is to be proved from circumstances, it is proper to
consider whether the child had attained that size and maturity by which it
would have been enabled to maintain an independent existence; whether it was
born alive; and, if born alive, by what means it came to its death. 1 Beck's
Med. Jur. 331 to 428, where these several questions are learnedly
considered. See also 1 Briand, Med Leg. prem. part. c. 8 Cooper's Med. Jur.
h.t. Vide Ryan's Med. Jur. 137; Med. Jur. 145, 194; Dr. Cummin's Proof of
Infanticide considered Lecieux, Considerations Medico-legales sur
l'Infanticide; Duvergie, Medicine Legale, art. Infanticide.